Train telephone system for simultaneous communications



A. G. sHAvER "TRAIN TELEPHONE SYSTEM FQR 'SIMULTANVEOU$ COMMUNICATIONS Original Filed sept.V 19, 192s; 2 sheets-sheet 2 Y hb- Gm. 4 @t .2; .Ww m2 Y Nw 'INVENOR R E v` A H S.. G D L A ,m H G R. A

Parenteel'MY1:191'938'5 y h `TRAIN' TELEPHONE SYSTEM FOR f TANEOUS COMMUNICATIONS alcalina o'. shaver, chicago, m.

Anuman mummia, loza. serial No. 306,905' BcnewedFebrllary25, 1932 This invention relates to a system for carrying `on communication between diilerent Pparts of `a. railway train; between two railway trains operating on the same track system; audbetween a v` railway train and the wayside. More specifically it admits of two or moreseparate and distinct sets oi' communications taking place atthe same time over the same general system, as for example:- Colnmunication may be carried on between adis'patcher in his omce on the wayside and either the conductor` or engineman, or both of them,` on l atrain at the same time that communication is taking place between a'pas'senger on the train and some person in a wayside station: Or it may V be that` communication is taking placebetween v fthe engineman at the heado! a train andfthe conductor .at the rear of the train, and. at the jsame time communication is under way between a passenger on the train and some person in a wayside station, or `on'arlother train. y

A principal :object of the present invention4 is the provision'lof a system embodying improvements inthe communicating means, employed as a part ot the tr'ain operating system, described and claimed in the copending application of f 'ArchibaldGJShaven Serial No. 227,932 filed Ocl tober 22, 1927,'in which communication may take place between thengiuem'an at the head of the Y cram and the conductor at the rear of the mun,y j 3'0 or between either o! these latter two, or both of them, andthe train dispatcher while the train is movlngpr standing still and the dispatcher is in' his oilice. The present case also represents a further development of my train telephone system application, inedl september '1,' 192s, serial No.

A further obiect oi' the invention relates to the provision' of means `for carrying. on a plurality oi' communications overv the same general sys- 0 terno!` connecting circuits without ,detrimental interference between the various? sets of com@ municatlons. i

The improvements in the present invention center 4about the application of audio ando radio frequency means to the novel means .provided for so connecting two parts of a train, two trains,'and

l 4 a train anda wayside station together for 'communication purposes, that twov or moreseparate and dlerent communicationsmay be carried on at. the" same time over the same communieating medium. l V

- In the drawings, .which'show a preferred embodiment' of the invention: l f

Figure `11 is a4 schematic diagram of the circuits `5 5 andv equipmenton one or bothy ends ofthe o of circuits and equipment o I frequencies, of a band somewhat higher than the 'a 'stretch of track. C A represents therear end carmenl sets luustrated 1n Figures 1 and a. 5 l

Figure 3 illustratesthe usual arrangement oicircuits and equipment for the head endo! a train.

Figure 4 is another and o tional arrangement dnf train.

Figure is a diagrammatic showing illustrative ot circuits and, equipment lon the wayside to co-gordinate with the train carried'set illustrative in Figure 4. o v

The system will new .be described as one for telephone communication .in which audio irequencies are used for the business of the railroad (for communication between conductors and enginemenfand the train "d1spatcher); and radio 'audio band, are used for commercial purposes (for communications between passengersA on l trains and persons in wayside stations, and bef tween passengers on diiIerent trains).

In Figure 1, .the boundary/line BYIO -encloses 25 the radio frequencyL equipment and the boundaryv line BYII encloses the audio frequency equipment, all onthe train. T3 is the radio frequency transmittingmeans inla circuit including conductors 200 andj20ll, modulator and oscillator MilOl, conductors 20| and 201, filter FL2, con-I ductors202 and 203, inductor INDLconductorMll,d inductor INDl and conductors 205 and 200. R3 is a radio frequency receiving means in a circuit including conductors 2|0' and2l3, detector DET3. conductors 2li and 2M,- lter FLI, conductors v 212,l 202- and203, inductorINDl, conductor-'20l, inductor INDS and conductors 205 'and.2l5. The

audioufrequency system comprises transmitting and receiving setsy Z3 in a circuit including con-l ductor 2li, nlter FLA, conductors 2i0 and 20.3, inductor INDI, conductor 20I, inductor.` INDl and conductors 205. and 2|0. "1he inductors IN'Dliand ISNDly are oi' suitable design and so in' inductive cooperation with said track rail positioned thateachrides over a Vtrack rail TR through an air gap. While these inductors are lhere shown connected in series, they may b e conlnected in parallel; and the system is operative if only one inductor is used.

.In Figure 2, two complete intermediate circuits.

B- C andD-E, and parts voitwo others; A- and-M f are illustrated. TR are the track rails'of and LQ the front end of a train.` Also, those same symbols, minus the connecting line, may be understood totrepresent two trains in the same intermediate circuit, CA being one train and L the other'train. TAR is a control relay which is '5 deenergized during and by the presence of a train in intermediate circuit o section A, but otherwise energized. TB, TD and TF are track k circuit relays of` the usual sort normally energized, but deenergized, whenever there is a train in their respective sections B, D and F. TA, TC and TE are telephone transformers each with a primary'P and a secondary S. L isa conductor extending throughout the length of the stretch of track which is equipped for train communication. DI and D2 represent the two conductors of a wayside telephone system, as for' example the well known dispatcher's telephone and selective system now in use on nearly all railroads.

SL is a selector relay operated by the selective system, which is ordinarily a part of the dispatchers telephone system for calling operators in wayside stations to the phone'. 4 6 and 41 are 'circuit making contacts normally open but closed when SL is operated by the prescribed code in the selective system when DSA Vis operated. V

For the intermediate circuit A the partial circuit conductors L and 32, secondary coil'Sof The intermediate circuit D-E comprises track rails TR, connections to condensers AC, conductor 40, contact 4I normally closed, conductors 43, L and 52, secondary coilJS of transformer TE, conductor 53, contact 5i normally closed, conductor 5l, condensers AE and connections to the track rails.

For the intermediate circuit F-G thepartiai circuit track rails TR, connections to and condensers AE, conductor .53, contact 5| normally l closed and conductors 53 and L, are illustrated. That part of intermediate circuit F-G not shown -is like that illustrated and described for inter- 'medi'atecircuitA. r 55 The heavy lines across the track rails TR as indicated by 24n are insulated. joints fixing .the limits of the track section circuitsA, B, D, F, etc. In order t make the track rails part of the in-n termediatel circuits c'ompletefor conducting the o0 communication currents, a condenser -TK is connected around each insulated joint as illustrated.

Within the boundary line BYI2 are represented the radio frequencycircuits and equipment in the waysidestation. T4 is the radio frequency duetorsflgs and 229, modulator a'nd oscillator v l `limohconductors 221 and .230, filter FIA, conduct'ors 225, DI and, condenser EC,.primaryr 'con P of transformer TE, and conductors u, Dz,-

ansformer'TE and conwithin the boundary une BYn are represented the audio frequency circuits and equipment in the wayside station or dispatchers oi'iice. Z4 is f the transmitting and receiving set in a circuit tion. Transformer TC is connected only when 15 the selective system device DSA' is operated to energize relay SL to close contacts 46 and 41. Transformer TA is connected to conductors DI and D2 whenever there is a train in section A so that relayjTAR is deenergized. praetice'one, any two or all three of these methods of connectionmay be used within the corn-y pleted system.

' DSA represents selective apparatus of the type l now used in railway telephone systems for dis- 2;, patching trains. This apparatus .is operatedvto connect the conductors DI and D2 to the transformera, as TC, whenever it is desired by 'thevdispatcher to hold conversation with a train vin a particular intermediate section which is equipped 30 a for selective connection.

JI' is a disconnecting switch shown merely as a convenience for disconnecting the station equipment from the outside lines.

',Flgure 3 illustrates the equipment which will 35 lusually be installed onthe head end of the train4 and it isfor audio frequency operation. Generally the equipment on the head end of the train is for the use of the engine crew in conversing with the conductor and dispatcher, hence from 4oit only one conversation at a time is necessary.

` In any case where niorethan one setof .com-

munications is to be under way at one time from the head end'of the train, the equipment and circuits illustrated in Figure 1 would be used. ZI 45 isthe transmitting and receiving set in a circuit including, lconductor 231, fnlter FLE, conductor 235, inductor IND5, conductor 235, inductor INDI and conductor 234.I The inductors IND5 and lIND4 arealso positioned to ride over the track 50 f of system for making possible 'the vsimultaneous l transmitting and receiving of a plurality of oommunications to and from a train. In this system 4 audio frequency is used for one channel of com 0 0 munication and radio frequency for another channel. It differs essentially from the system heretofore explained, as illustrated in Figures 1,- Ii. and 3, in that each channel of communications has acircuit of its own and each track rail is deo5 voted to, a different intermediate :circuitso that for each section of trackthere are two parallel intermediate circuits, one: of these 'intermediate lcircuitsrbeing used for the audio vfrequency communication and the other for the radio frequency communication, -These intermediate circuits oonnect to differentsets of wayside lines. In Figure 4". the boundary line B21 encloles,

the entire equipmenton the train for'one let.

If there is a s econd set,y it may be a duplication .75

In actual 20 ci the acne shown. ordinarily. however. vtneceet at the. head o! the train will comprise the audio frequency equipment only which isl that' including the transmitting and receiving equipment Z1,

5 the iilter FLC, the inductor IND8 and the con- Y necting ycircuit composed of the conductors 200 and 80|. 1

, 'I'he radio frequency set comprises the transmitting apparatus T8 and the receiving apparatus R5 connected to the Inductor IND1. The transf mitting apparatusl T8 is in a circuit including i modulator and oscillator M&O5, filter FL8, conductors 802 and 800, Inductor IND1 and conductors 301 and 808. The receiving'apparatusR! is ina circuit including detector DETI, i'llter FL1, conductors 804 and' 80|, inductor IND1 and conductors 801 and 008. I'he inductors IND1 and IND8 are of suitable design for. the frequencies tion with `said rails through an air gap.' i

Where both ends of the train are equipped with communicating sets', the inductors will be positioned in accordance with their respective intermediate circuits. If onel end ofthe train is' equipped for audio frequency operation only, the

inductor for that set'will be positioned over'rail TRI. In the case of trains operating in both directions on one track, it will be necessary that in- 30 ductorsv be provided for each direction of operation; or the inductors may be interchanged in' "455 |08. contact- IBI Anormally closed, conductor |52 Thatpart of and condenser to track rail TRI. this intermediate circuit AI not shown is like that illustrated and described for intermediate circuit FI--GI including. conductors L and III, contact' :.:i III, conductor Ill, condenser and track rail TRI. f Section BI-CI, complete circuit, track rail TRI. condenser, conductor |52. contact |5| norformer RCI. conductor I l1, contact |55 normally closed, conductor |58 and condenser to track rail Section DI-EI,

TRI, condenser-and conductor |88.' 'contact III 4normally closed;` conductors |81, Li and |88,

mi transformer REI, conductor Ill, contact |80 normally closed, conductor |88,condenser and track -railTRL` section ifi-cil, partial circuit 'only shown,

-.-track rail TRI. condenser, conductor |80, contact i* |88 normally closed. conductors I II '.Ll, etc. That part of this intermediate circuit` FI-'GI not shown is likethat partial circuit illustrated and described for intermediate circuit AI including municating' current will have anvuninterrupted 'u cath through the track rail Tai, condensers `tire used and positioned to ride over the trackrails TR2 and TRI respectively in inductive coopera' used I 4,'trans-y many cl conductors 'sa' L' and s wayside station or dispatchers oilice.

'complete I circuit,v track mii connected es illustrated in Fig. 5.' e'rcund au insulated joints.

For the-radio frequency operation the interme f diate circuits are:

Section AI, partial circuitonly shown, conductorsLG and |80, transformer TAI conductor 188,' 'contact I8I normally closed, conductor |82, and 'condenser -to track rail TR2. That part of thisintermediate circuit AIy not shown is like that illustrated'and described for intermediate circuit Fig-GI,,includingyconductors L8 and I 8| con tactv|89, conductor |90, condenser and track rail TR2, condenser, conductor |82, contact |8I norkmally closed, conductors |83, L6 and |84, trans'- former TCI, conductor |81, contact |85 normally closed, conductor |86 and condenser to track rail 'Section DI-`E|, complete circuit, track rail TR2, condenser, conductor |86, contact |85 normally' closed, conductors |81, L6, and |88, transformer TEI, conductor- I9I, contact |88 normally closed, conductor |90 andcondenser to track rail TR2.

. i Section F|-GI, partialcircuit only shown,

track rail TR2, condenser, conductor |90, contactthrough the track rail TR2, condensers are 'connected 'around the insulated joints' as' illustrated in Fig.l 5. i

Within the boundary line BY8 are representedthe radio frequency apparatus and circuits in a wayside station. T1 is the radio frequency trans- `mittin'g means in a circuit including, a modulator and oscillator M8101, filter FL8, and conductors M8 and 8 I2 and 309 and 8|8 connecting to telephone conductors D1 and D8 which extend along the equipped railway track. 4R1 is a radio frequency receiving means in a circuit including, detector DET1, iilter FL8 and conductors 3I0 and 3|2 and`3II. and 3I3 connecting to conductors D1 and D8. f

Within the boundarylineBYS Aare represented the audio frequency apparatus and'circuits ina lZI; is the transmitting and'receiving set in a circuit'including filter FLD and conductors 3| 5 and 3M` connecting respectively tov4 telephone conductors D5 and D6 which extend along the equipped railway track. 5

CAI represents the rear end of a train and operating the selector relays SLC and SLE.

TARI, TCRI and TERI are controlrelays nor-e.

mally energized, but decnergized with the presence oi' a. train in their respectivesectins All, BI-CI and DI-EI., TBI, TDI-and 'I'EI are track'circuit relaysof the' usual sort normally the track rail TR2 are insulated 'joints limiting the various track circuit sections AI, BI, D|,FI, etc. In'order that the communicating ,current will have an uninterrupted path section BIL-ci, complete circuit, track aii energized, but deenergized with a trainin their i respective sections BI; DI `and FI.

designed for radio frequencies, the secondaries of each being in the normally closed radio inter'- mediate circuits for sections AI, BI-CI and DI--EI respectively, and the primaries being connected to wayside telephoneconductors D1 and D8 whenever relays TARI, TCRI and TERI respectively are deenergized operating their back contacts to the closed position. When back contacts |62 and |63 are closed, leads |1| and |12 of primary coil P of transformer TAI are connected to conductors and |16 respectively. When back contacts |66 and |61 are closed, leads |92 and |93 of primary coil P of transformer TCI are connected to 'conductors |94 and |95 respectively. ,When back contacts |69 and |99 are. closed leads |98 and |99 of primary coil P of transformer TEI are connected to conductors |99 and |91 respectively. .Conductors |16, |95 and |91 are connected to conductor vD1.y Conductors |13, |94 and |96 are connected .to conductor D8.'

'Ihe transformers RAI, RCI and REI are .de-

5 signed foi' audio frequency, the secondaries of each being in the normallyclosed audio intermediate circuits for sections AI, BI-CI and DI-EI respectively. .Leads |13 and |14 from transformer RAI are connected to telephone conductors' D9 and D5 by the closing ofv contacts |84 and |65 on conductorslill and |19 respectively. Transformer RCI is bridgedacross telephone conductors D5 and D6 when selector relay SLC is operated by the train dispatcher to close contacts 3BG and 3|1. rTransformer REI is similarlyy bridged across the conductors 'D5 and DB' by the closing of contacts 3| 9 and 3I9 in the operation of selector relay SLE.

In the -system illustrated in.FiguresV 4 and 5,

. 'thef use ofone radio-frequency band andl one munications. Since there-are twoseparate and audio frequency has been referred to for ltransmitting and receiving simultaneous sets of comdistinct communicating lcircuits orchannels throughout the system, it is readily apparent that audio frequencies alone or radio frequencies in the same band,'or radio frequencies in diiferent bands may be used, instead voi the one4 radio frequency band and one audio frequency band, for simultaneously carrying on a plurality of Y sets of communications.

ing/transformer' TA vwith conductors D2 and DI.

to give order's tothe train conductor using the equipment -represented within the boundary line B YfIIr Also assume that at the same .time a Aer on the train, using the equipment represented within the boundary BYI Il, starts a con- -versation with a person in a wayside station, 1 usingl the equipment within the boundary line BY`I2. The 'trainfbeingin' section A, relay TAR is deenergized closing contacts 34 and 39 connect- The dispatcher makesit known-to the train conductor' through the equipment za, by causing. electric communication impulses to be set,-

- up in the channel `for `communication hereinafter described, that he desires to communicate with him. The train conductor receives the signal through the receiving equipment of Z3. and answ'ers through the transmitting. equipment of DI and D2 to transformer TA, intermediate eircuit of A already described, the inductors 4INDI andv IND4 and conductors 294, 209,v 2|3, 293, 2|! 10 and 2|1, andtransmitting and receiving set Z3. Since this conmiunication is carried on yat audio frequency filters FLB and FLA are adjusted to let electric currents of audio frequency through, but none other. Since lters FLZ, FL3, vFL4 and 15 FL5 are adjusted for the particular` radio frequency band usedin this set up,-they do not pass electric currents at audio frequency; hence receiving equipments R3 and R4 are not disturbed by the communications transmitted at audio 20 frequency. i A In, the meantime the passenger with transmitter T3 and receiver R3 has entered into communication with a personv using transmitter T4 and receiver The :channel for these com- 25 munications is also via the inductors IND3 and IND4, the intermediate circuit of A including the transformer TA, 'and the conductors DI and D2, and vice-versa. Since this communication is carried on at radio frequency and the filters 30 FLB and FLA are adjusted for audio frequency only, electric currents of fthe radio frequency band used are not passed into the circuit of Z3 and Z4; hence the communication being carried on between the dispatcher and train conductor 36 vIn the operation of the'system, electric cur- ,rents induced into the intermediate circuits 40 through the transformers, as TA, set up a field of electro-magnetic impulses surrounding the track rails TR.. This electro-magnetic field influences the inductors on the train to set up currents of similar 'impulses in the circuits of the induc- 45 tors, thus affecting the receiving apparatus on the train. n A .In the case of transmitting from the train,l the electric currents in' the inductor circuits are transmitted inductively into the track rails and 50 thus into the intermediate circuits and through the transformers, as,TA, to the circuitincluding the conductors DI and D2 and the wayside receivingequipment, aifecting the latter -to give the required signals. While the train Isin section' A, the intermediate circuit of A being automatically connected to the wayside circuit,'includi ng conductors DI and D2 leading tothe wayside stations. communications may be freely carried on and at will be- 60 tween the train and thevwayside, either station initiating.the communication. L i Assume the train to be in section lB--C and that simultaneous communication is entered into between the train conductor at the rear of. the 05 train CA and the engineman at the head of the train LO, and between a wayside person and a passenger on the The conductor initiates the vcommunication by operating the transmitting equipment of Z3'. 10 This sets up audio frequency' current in thecir- 'cuit affecting the inductors mm and motto induce'audio frequency impulses into ,the track ,rails-'I'Rjsuch that the intermediate circuit. of

B-'C heretofore described energized with audio 1l 20 i nated as-DSA. The closing-of the conta'cts 46 so now communicate with the passenger through frequency currenti s the induetorsy IND5' and l relation with the track railsA TR, audio frequency INDS at the head of thetrain LO are in inductive current in these track rails isL induced into the circuit of 'said inductors and the communication is received by the engineman at Z'. When the engineman replies to the train conductor, the audio frequency current initiated by lhill through the transmitting equipment of Z5 in the circuit for the inductors IND5 and INDE is induced into the intermediate circuit B-C and reinduced from saideircuit "into the circuit ofinductors IND3 and IND4 thus affecting the receiving apparatus e Z3 so that the conductor hears the enginemans signals.

For the wayside person to'communicate with Ithe passenger, selector relay SL must -iirst be ,j present day telephone exchanges.

operated to close the contacts 46 and 41 which is don'e by operating the selector from the proper code key in the selector ,system generally desigand 41 may also be done direct by the wayside person in the usel of the dial system of. an automatic telephone system identically as. is now accomplished, in machine switching lfor connectingr one subscriberv with another-in many of the With contacts 46 and 41 closed transformer TC is connected to wayside communicating circuitV conductors DI and D2.' .The .wayside personmay transmitting equipment T4, `conductors DI and D2, transformer TC, intermediate circuit B-C,

' inductors IND3 and IND4 and receiving apparatus .R,3. The passengermay respond into transmitter T3, 'through thefsame .channel described, to the receiver R4.

since alters Fm, r1.3, Fu and FLs are adjusted to th'e radio. frequency band and will not pass the audio frequency and since the filters FLA and FLB are adjusted to the audio `frequency, and will' not passfthe Vradio frequency band; the simultaneous communication between train conductor and engineman an`d vbetween wayside .person and passenger may becarried on without interference, one' Withthe. other.

- Assume that CA and I IOl are two differentl trains,- but both in ,section B-C; andsimultaneous conversation takes place between train conductor of LO and train conductorfof CA and between a passenger on yL0 and a passenger on CA. The procedure and' method for communicating between'the twc train conductors is the :same as alreadyexplained for communica- `tion between the train conductor and engineman ofthe same train. 'Ihe procedure. and method for communicatingbetween the passengers of the two trains issimilar to that Lalready explained-for the communication between the train conductor and engineman of the same train, except radio frequencies are `used for the passenger to passenger communication. Because the filters of the audio frequency system `will not pass the radio' currents and the lters of the radio frequency systemwill not passthe audio v currents,l thetwo setsv of' communications lmay be carried on simultaneously. A set of ,com-

munications, herein referred to, consists of themessages 'exchanged betv'en tw`o"`"'persons communicating together;

Refer now to the system disclosedgin Figures 4and'5: A f Assume the ltrain to be operating through the sectionn'BI--CI as illustrated, being equipped on the ear end CAI, as indicated in Figure 4, and

5. that simultaneous communications are carried on between the train dispatcher, at the station enclosed in boundary BY9, and the train conductor, using transmitting and receiving apparatus Z1,

and between a wayside person, using transmit4 5 f I ting apparatus T1 (and receiving apparatus R1,

- transformer RCI and track railTRI already described, Inductor INDII andthe circuit to receiving equipment Z1. The train conductor by. operating the transmitting equipment of Z1 may reply to the dispatcher through the'same channel of communication, sequence reversed, for re- `ception bythe dispatcher in the receiving appa-r Y vratus of Z6.'

while the' train 'is within che section Bl-'CL control relay TCRIsis deenergized closing its con- '30 tacts |65 and |61 connecting the wayside tele-i phone circuit D1 and D8 to transformer TCI s'o that the wayside system includingA the stationv within the boundary line BYB, is connected to the intermediate circuit-of section BI-CI in cluding transformer TCI and track rail TR2.

Through the transmitting equipment T1 the wayside person may `send signaisto the passenger, the channel of communication being conductors D1 and D8, transformer TCI, intermediate cir- 40 cuit of BI-f-CI including track rail TR2, inductor IND1 and.` circuit to receiving equipment R5.

-The passenger by communicating through trans- "mltting equipment T5A may reply through` the same channel, in reversed sequence, to the wayside person at the 4receiving equipment R1.

As heretofore explained, the operation for communication between train equipments T5-R5 and wayside equipments TI-R1 is byfa band of radio frequency while the operation for communication between trainiequipment Z1 .and wayside equipment ZG is by audio frequency. The lters-FLB, FL1, FL8 and FL9 are adjusted to passthe radio frequency band while the filters FDC and FLD are arranged to pass audio frequency. This provision for ptwo different fre`l quencies is made lmainly for the purpose of prie-V ventirg'interference, as cross talk, which mightv result in some cases, particularly as between the track railsTRI and TR2.

There may besimultaneous communications consisting of a conversationbetweenthe rear end CAI and thefront end LOI of the train and a 4conversationbetween a.4 passenger on thel train y and a .person on'the wayside. The front end of 65 train must have an equipment identicalwith inductor INDB audits circuits including transmitrting and receiving equipment Z1. The train conductorfitalking vinto transmitter aequipment Z1,

has his lmessage conveyed by audio frequency via Inductor INDB, track trail TRI and intermediate circuit, inductor INDB and circuits onfront of the train to receiving apparatus Z1 on front ofv the train where the message is received by the engineman. The engineman replies to the train` conductor through the same channel of communication, sequence reversed. While the conversation between the train conductor and engineman is going'on the er 'talks into transmitting equipment '11 to the wayside person and his communication is carried via inductor IND'I, track "rail TR2 and( intermediate circuit Bil-CI, transformer TCI,v wayside circuit conductors D1 and D8 and receiving equipment R1. The wayside person replies to thepassenger by talking into transmitter T1- and his communication is carried by the channel just described, in the re-4 verse sequence, to receiving apparatus R5.

Conversations between parties .on two dliferent trains in. the same intermediate circuit are conducted in the same manner as between heady end and rear end of train. Two sets of conversations may be carried on at the same time,

of communication, that carrying radio frequency,

are always in operative relation as theV train progreases over the railroad, the train automatically connectingthe intermediate .circuits with the wayside circuits as'it passes through the section for each circuit. For the other channel of communication, that carrying audio frequency,

:the treineireuits end the wayside eil-cuite ere lalways in operative relation while the train is in section AI, because of the train on the track tablish operative relationship between the way-y rails automatically connecting the waysidecir cuit with the intermediate circuit through relay TARI; but for sections BI-CI and DI-EI the selective system must be operated in order to esside and train circuits for the audio frequency.

These various methods -of coordinating wayside and train carried circuits are typical. Any one method or 'any two or more of -the several methcds indicated, may be used, dependent upon the f local conditions existingn the railroad equipped. For the conduct of the railroad business, it is generally best to provide an arrangement which Will allow the greatest Dylble freedom for intratrain (head end to rear end) and inter-train (train to train) communication .and at the same time give the train crew an occasional opportunity to initiate a conversation withthe dispatcher.` With the selectivel system ythe disl patcher can always get into communication with a train. After thelselective system' has been operated connecting thewayside system-with 'the intermediate; circuit and communication has ceased. the wayside systemv is disconnectedi'rom the intermediate circuit by vagain operatingfy the selectivesystem. v

The condition existing where a. train `posses from one 'intermediate -e'ireuit te another ismuy` described in my copending applications Serial No.,

,932 med October 22 1927 am! SerlaLNo.

304.433 'med september "1. 192s. i 1

.liefen-ingcorrigeren2mais.atriiininpe'sine` imm' enefintermediate eireuit te another uw matically opens the cross connection fir'om the.

parallebconductonl'i to sothat Vdlrilltthe interval oflpassIng-these two adjacent intermediate' circuits thrown `togetllierinto orseveralrradio bands, each one enlarged intermediate circuitor communicating zone.

This condition may be specifically illustrated byreferring. to Figure '2 and -assuming a train `possingfrom intermediate circuit B-C to intransformer TC is shunted from the circuit; but Y as front contact 4I opens, creating the enlarged' intermediate circuit, the transformer TE is made available as a part of the enlarged intermediate train. -While the train isiwithin this enlarged intermediate circuit, that is while any part of the train is within the track section D, communication carried on between vthe front and rear o! the train, between the train and a wayside station, or between the train and a second train, should there be a second train in section `B--43, an enlarged intermediate circuit as for sections B-C plus D-E, Ithe intermediate cirycuit for section D-E, etc., a travelling intermediate circuit or communicating zone being In reality created by this arrangement. v

In Figure 5 a trainin irom-oneintermediate section, as BI-CI, to another intermediate section, as DI-f-EI, deenergises the track circuit relay, as DTI; thus causing each ot the two intermediate circuits, as for section BI-CI (one including the track rail TRI and the other including the track rail TR2) to be combined with the respective intermediate circuits oi -the adjacent section, as for section DI--EI (one including the track rail TRI and the'other includingthetrackrailTRI). WhenrelayTDIisdeenergized, back contact II! is closed shunting transformer RCI and connecting conductor-Ll 'circuit forl communication between wayside and oi' section `BI--CI with conductor Llof section I DI-EI.; also back contact III is closed shuntingtransformer'rclandconnectingconductor'- cation sone travelling with the train which corn-I the .two intermediatecircuits, one eacli'or TRI and s In the we systeme: eemmumeetiennerem described, as illustrated injl'lgures i. sand 3 and .4 end 5,31 neveshewnfseeineeny newwev eu of eonve'rsatims, orcemmunicationamay becarnedenez me nmetime. simula omebeineedw for communications. or additional sets otfcommimicationato be carried '.on simultaneously With'tpode'deactlhedg'it Il 0bvious'the'ssmemaybe-donsby providingvothsr,

M l, enligne f thevehicle for transporting theadditional sets i of communications over the same'circuit medium.

` `frequencies 'for conveying said Isets of communications one band for each set, and circuit means l `roadside transmitting devices vwith said train- What I claim as new is: 1.-In a system adapted to simultaneously i transmit a -plurality of sets `of communications between av railway train and the roadside, the combination comprising, transmitting and rei i, ceiving devices on'the train, transmitting and receiving devices on the roadsidesaid 4transmitting devices generating bands of electric current including the track rails adaptedto' inductively connect said train carried transmitting devices with said roadside receiving devices and said carried receiving devices, for transporting said electric current frequency bands. y

2. In -ak system adapted to simultaneously transmit two sets -of communications between a railway train and the wayside, thecombinatlon "comprising, audiofrequency transmitting and receivlng meanson each said trainv and said wayi side Afor transmitting and receiving one set-of said,A communications, a' radio frequency trans-' mitting and receiving a.meiifnson eachl said train and said wayside for transmitting and receiving the other set of saidcommilnications, and circuit means, including the track rails in multiple, elecl trically related. to the train carried means and i, adapted to be connected to said transmitting and receiving means on the wayside `for carrying said audio and radio current frequencies .between said `train and said wayside.

3. In a system adapted` to sinilultaneouslyy transmit a plurality of sets of `communications between a railway `train vand the wayside, the

combination comprising, means on each said train and said wayside for transmitting and receiving a* plurality of frequency bands,'one,band

` for each of said sets of communication, and circuit means in electrical relation with said train means adaptable to'be selectively connectedwith `said wayside transmitting and receiving means.` 4. In a system adapted to simultaneously l transmit a plurality of sets of communications between two railway trains on the same track system, the combination comprising, means on each vtrain for transmitting and receiving a plurality of frequency bands; each'band carrying one of each sets of communications, and circuit means forming a communication zone travelling with the trains, electrically related to` said. train means, for fconnecting'the transmitting and receiving means of one'train with thetransmitting and receiving means of the other train.

5. In a system for, carrying on two sets of communications between` a` railway train and a wayside station, a track. system connecting comf munication devices on `"said train with communication devices on said wayside comprising, an

y"intermediate circuit including oneof` the rails 05 of the track, another intermediate' circuit including the iother rail of the track, both of said L track rails being in inductive relation with 'the train devices, and means operated by the presset ofl communications.

ence `of the' train on the track connecting. one in- .7`0 tcrmcdictc circuit with 'come cf uic wcysidcdcvices for transmitting to and recelving'fl'om the train one setof communications, Iand selective means for connecting the other intermediate circuit withother of the wayside devices for transmitting to and lreceiving from the train the other s. m ccnilmnaicn, c railway track formes in sections, a plurality of conductors` parallel thereto, a radio frequency wayside station connected. f

to a pair of said conductors, an audio frequency wayside' station connected to another `pair of' scid conductors, track, relay controlled circuits for electrically connecting said radio frequency pair ofk conductors in operative relation with one rail of saidytrack 'and means electricallyr conf necting said audio frequency pair ofconduct'ors to the other rail of' said track.

'7. In combination, a railway track, aplurality of pairs of conductors parallel thereto, aradio fren quency waysidestation connected to a' pairofsaid conductors and'an audio frequency wayside station connected to another pair of said conductors,

a pairv of transformers one having its secondary. Y terminals connected to one of lsaid 'rails and the other having its secondary terminals connected to the other of said rails, switches for connecting the' primary of one of said transformers to one l of said pairs of conductorsf'and additional `other of said rails, switches for connecting the primary of.` one of said transformers to oneI of 'said pairs of conductors, additional switches for connecting the primary of the other transformer` to the other of said pair of conductors, an audio frequency wayside sending and receiving set connected to one of said' pairs of conductors, a radio i frequency wayside' sending and receiving set connected to the other of said pairs of conductors,

and a railway trainE on said track having an audio frequencyreceivingqand sending set connected inductively to' oney rilof the trackand a radio frequency receiving andsending set connected to the other rail of said track.

9.l In a train communicating system, the combination comprising, 'a first anda second communicating station for a train, a first and a second communicating station on the roadside, and means creating a transmission medium traveling f with said train adapted to so connecttogether ysaidstations that communication may be car- Y ried on between said first stations exclusivelyy at the same time that communication isbeing ,car-

'Aried on between said second stations exclusively. l0. In a train communication system, thecombination comprising, a first train station, a vsecond train station, a first roadside station, a sec--MA ond roadside station; and means, controlled in part by the train and in part from a roadside station, adapted to continuously connect together said first stations and said second stationsl as the -train travels` over the railroad, so that un interrupted communication between said first i stations and uninterrupted communicationk between said second stations simultaneously.

may be` carried on4 11. In a train communication system, the com- I l' bi'nation comprising, a first train communicating station, a rsecond train communicating station, a first'V roadside communicating station, a second roadside communicating station'. wayside means,

including a series of wayside 'circuits in communicatlve relationw-ith said train stations, a wayside'communication circuit connecting to each of said wayside stations, circuit controlling means associated with said series-of circuits adapted to connect each of said series with vsaid wayside communication circuit. and means associated with said communicating stations permittingexclusive communication between said tlrst stations simultaneous with exclusive communication being carried on between said second stations. l

12. In a train communicating system, the combination comprising, a first and a second communicating station on a train, a first and a second communicating station o' the roadside, means traveling Vwith the train adapted to conneet together said stations. means insaid stations" for transmitting and receiving non-conieting" sets of communications simultaneously between said rst stations and between said second stations, and means associated with said stations maintaining the distinct existence of Ieach of the said sets of communication.

13. In a system for carrying on a set of communications between a car and the locomotive of a train and simultaneously a set of communicaf tions between said car and a wayside station. in combination, a plurality of communicating sets in the car. a commenting set in the locomotive harmonizing with one of the ear sets, a communicating set in the wayside station harmonizing with anotherof said car sets, a circuit meas on the wayside in normal 'inductive relationship with said car sets and the locomotive sets so that communication may be carried on thereover between thecar and locomotive. means adapted to Vconnect the wayside station set with'said circuit means that communication may be carried on over said circuit means between the car and the .wayside station at the same time that communication is under way between the car and the locomotive, and means associated with said car sets whereby the distinct characteristics of each set of communications is maintained.

14. In a system ior simultaneously transmitting a plurality of sets of .communications between a railway train and a wayside station, a`

` stretchbf track'for the train, train carried means for simultaneously transmitting and receiving separate sets oi communicationsfwayside station means for simultaneously transmitting and receiving said'sets 9i! communications, means electrically coupled with said train carriedy means and with the means forming said sone.`

controlled by the presence of the train in saidstretch forming a communication none for said trin to which the said sets of communications for and from said train are coniined, and means operative from the wayside station for placing said wayside station in communicative relation means and electrically.controlled=from said waysidefor placing said wayside means in communicative relation with the said means on each et a plurality'of said trains 16.'In a system for a plurality of communica- `tionssimultaneously'carried on' between vehicles -ina'section'oftrachmeansoneachvehiclc adapted. to simultaneously a plurality of communications. a conlnunication sone for said vehicles lwithin which communicameans contmued by said trains for placing sindy vehicles in communicative relation with each other. m 1 l 17. In a system for communication between two train stations and between one of said train stations and a wayside station. a channel for a traimof a loopr circuit including the running' rails in said stretch, radio frequency current generating means located at separated points onl a train and arranged for inductive co-opcration" with said loop circuit, and devices at'each train point adapted 4to modulate and demodulate said radio frequency current whereby vradio frequency signaling is effective between said train points through saidloop circuit.

19. In a telephone system for inductively receivingon a train a plurality of carrier currents of different frequencies, a stretch of track in cluding the two running rails for a train to run over, a conductive intermediate circuit, including electrical conductors, associated with' the stretch of track and electrically closed with the stretch of track either occupied by a train or unoccupied, operative with a train' running in either direction and adapted-toV change with a train moving over said running rails by additions to the circuit ahead of the trainand subtractions from the circuit behind the train, said change being dependent upon the movement of the train, a winding located on said trainin such manner that, with a train present on said `running the winding is disposed near to and separated by'd an air gap from one of said conductors of the intermediate circuit and, together with said conductor, constitutes an electrical transformer of l carried on said'train'in circuit with said winding adapted to he reeponsiveto a plurality of .currents of dinerent frequencies in said intermediate circuit.

20. In combination. a railway train. rails in .the track for'said train to run on, means located at one point on the train for transmitting modulated carrier frequencycurrent into a circuit which includes said running rails therein in multiple, and means located at a point remote from said train point and associated'with said circuit responsive to said carrier frequency current ilowing in'saidcircuit due to said lfirst mentioned Y 2l. Inasystemof communication for railways,

a transmitter at one station adapted to-transmit electric current ofv carrier frequency. modulated demodulatethegsamejanda circuit including-the running `rails of the railway track adaptedtoreoeivesaidcarriercurrent-fromthetransmitter at theon'e station fand'to `transmit', saidrcarrier current to the receiver at said remote station..

lng tothe point It intotheril tionsbetweensaidvehicleeareconiinetand- .1.

ningraib.

'1e -saidcarriercurrent'ncwingzin'therunning-raih in-thes'amedirectienatanyfinstantandreturn-- 22. In a train telephone system, a stretch Vtrack for a train, a train on the track. a trans(- j mitting device comprising afcarrier current generator and a modulator at one point on the train, a receiving device at another point on the train, and a circuit for conducting current from said transmitting device to said receiving device comjprising the two track rails and a common return "path so related to said rails that current flows `through the rails in muitipleyto points substantially aheadof and in rear ci the train.

23. In a train telephone system, a stretch of track for a train, a train on the track, a transf mitting device comprising a carrier current generator and a modulator on the train, a receiving device on the train, a wayside station, a transl mitting device comprising a carrier current vgenerator and a modulator at said station, a receiv- `ing device at said station, a circuit associated with said train carried devices comprising the two track rails and a common return path'so vrelated to the rails? that current flows through the 1 rails in multiple to points substantially ahead. of and'in the rear oi' the train, and a r'second circuit connectingsaid i'irst circuit to said wayside station devices. y

2 4. In a system tortransmitt'ing one set ot sig'- nals between two vehicles voi a railway train and another set of signals between one of said vehicles. and a wayside station. in combination, a circuit carried on one oi' said vehicles for transmitting and receiving two sets of signals, each of -a `dierent current frequency, a circuit carried on theother of said vehicles for transmittingl and receiving a set of signals of current otone of said frequencies, a circuit, at a wayside station" 'for vtransmitting and receiving a set of-signals of the other oi' said frequencies. and an intermedi.-

ate circuit including the track rails in multiple electrically connecting the transmitting and receiving-circuitso! said vehiclesand said wayside station for conducting the signal currents theref between. v v 25. In an electric transmission system for railways, in combination, a stretch oi railway track, a ilrst station anda second station each associ-f atedwithvsaid stretch oftrack at points remote `from Aeach other,l a transmitter at said first station vadaptedto transmit `electric current ot car-v rier frequency modulated with current of a ditthe track multiplaf arouse 28. In a train operating system, in combination, `a railway line, a plurality of vehicles on said line, a wayside station, apparatus at said station .for transmitting to each vehicle electric current oi' distinctive character. said current being different i'or each vehicle, a receiver 'on each vehicle responsive only to, 'current intended ionl'that vehicle', and a circuit in electrical relation with the apparatus at said station and the receiver on each vehicle for conveying said currents from the Vstation to the respective vehicles.

27. In a system for simultaneous transmission to arailway train of an electric current of audio frequency and an electric current oi' -radio irequency from dierent wayside stations, in combination, a stretch of track for the train, receiving apparatus on the train selectively responsive to each of said currents, a plurality oi -waysidestations, apparatus at one oisaid stations for transmitting electric current o! radio irequency, apparatus at another station for transmitting electric current of audio frequency, and an intermediate circuit in electrical relation with said receiving apparatus on said train and adapted to be connected to lthe transmitting apparatus at said wayside stations for carrying the electric signal currents between said stations and said train. f

2a. The combination-with a stretch or track,

and attain operating thereon, of two locations spaced apart on the train. a transmitting circuit including a generator of current of a predetermined frequency at each location, a receiving t ting a plurality oi non-conicting sets of com?` Vmunications between a railway train and the wayside in which a separate frequency band 'of electric current is employed for transporting each set of said communications, means carried on said, train and means located on the wayside for supplying, transmitting and receiving saidbands of current frequencies on the train and on the wayside, respectively, circuitrneans on the way- I side Ior receiving the transmitted current from either said train or-said wayside, and means operable to place said train means -in electric relation with said wayside means via said circuit -means for the transference,.between,. said train and said waysideoi'one or. more than saidirequency bands. I

- ARCHIBALD G. BEAVER,

one of j 

